In this installment, I’ll take a closer look at how the channel came to be a (sort of) discrete watercourse, to provide some context for later posts about today’s land and water quality. Other posts can be found using the tag watershed.

From Montreal to Providence to Trenton to Richmond, many of the East Coast’s great cities arose astride the “fall line,” an imaginary line along which its many rivers tumble from shallow rapids in the hills to slow, wide, sometimes brackish coastal estuaries. In an ocean-going era, such a location ensured easy access for oceangoing commercial boats, fresh river water, produce from farms upriver and fisheries downriver, and later to water power from the rapids or waterfalls alongside — all without the considerable downside of a coastal location’s vulnerability to frequent Atlantic storms.

[Minneapolis, built astride the falls of the Mississippi, could be considered the most interior of the East Coast’s fall line cities.]

Washington, D.C. is among these fall line cities, and its constant attempts to reshape the Potomac River’s banks also show the vulnerabilities that fall line geology also brings. Above Washington, the Potomac speeds through a narrow gorge, tumbling over its majestic Great Falls and past the high bluffs of wealthy towns like McLean, Potomac, and Georgetown. At Washington, three flows of water conjoin: the slower and broader Potomac, Atlantic seawater that tides pull all the way up the Chesapeake Bay and the Potomac estuary (with tides rising to 3.5′), and several surface flows. The comparatively flat topography of the L’Enfant City results from it resting upon a “shelf” of sediment brought there by the Potomac over time. This 1861 bird’s-eye view map by John Bachmann (from the Boston Public Library collection) plays up the topography, dramatically showing how the character of the Potomac valley changes at Washington:

Several surface flows join the Potomac at Washington, notably the Anacostia River, Rock Creek, and Four Mile Run, but also several streams that have since been buried like Tiber Creek and James Creek. (David Ramos has compiled an impressive map of these buried streams.) From the very beginning of the city in 1790, plans were made to tame these streams for human uses like shipping. A map from the 1790s, drawn by John Russell, shows how city fathers, Pierre L’Enfant among them, conceived a system of drainage improvements. These canals were straightened channels based upon the east-west Tiber Creek and the north-south James Creek, both arising roughly where Garfield Park is today at the foot of the Capitol. The map also shows the outlines of the deeper, more easily navigable channels within the mostly shallow Potomac:

This idealized 1852 view, published by E. Sachse, illustrates the canals in an improbable shade of blue:

Shortly after Washington was founded, the Potomac’s plentiful sediment became a problem for the growing city. Land clearance for forestry and farming upriver combined with increasing levels of urban pollution dumped into local surface waters, making the water noxiously polluted — particularly during low tide, when pollution festered in exposed tidal marshes. The insalubrious tidal marshes at the mouth of Tiber Creek, beginning at the foot of the White House, appear to have given rise to the widespread myth that “Washington was built on a swamp.” The marshes are visible in these digital reconstructions of the 1791 shoreline:

The sediment buildup also threatened the city’s access to maritime trade. Given the marshes along the Tiber, the new city’s only shoreline adjacent to a deepwater channel within the Potomac was along its southwest waterfront. Wharves sprang up along Maine Ave. SW, landing fish and ferries that went to Alexandria and points beyond. In this process, this shore gradually urbanized and gained a “coat of armor” as buildings crept up to the water’s edge, as shown in this 1883 drawing by A. Sachse:

Private property owners’ interventions to shape the shoreline would soon be dwarfed by Congressional plans, particularly as the sediment threatened the relatively deep channel fronting Southwest’s wharves. Engineers (notably Peter Conover Hains) from what would become the Army Corps saw an opportunity to tame the city’s shoreline, preventing severe floods like that of 1881 from reaching the city’s core. Meanwhile, planners saw the potential for new parks — simultaneously adding land to the capital of a fast-industrializing country, meeting a post-Civil War national zeal for commemorative monuments, and providing Washington with a vast expanse of parks at its doorstep (as the fin-de-siecle era’s vogue the City Beautiful demanded).

This 1888 map by E. Kurtz Johnson depicts an early “cloverleaf” plan by Hains for filling in much of the Tidal Basin area, leaving a series of small pools that would be used to flush a new Washington Channel downstream:

In 1901, the City Beautiful reached its apogee here in Washington with the McMillan Plan. Shortly thereafter, the canonical birds-eye view of Washington had shifted 270 degrees; instead of placing the Capitol dome front and center with the filthy Potomac River in the distance, now bird’s-eye views proudly showed off the carefully sculpted shoreline, with its large and scenic Tidal Basin, an urban shoreline for the Washington Channel, and probably many more trees in Potomac Park than existed at the time (1916, drawn by H. H. Green):

Updated 17 May 2015 to fix broken links. The USGS recently made turn-of-the-century maps of DC available (the 1:62,000 scale is best); most show the Channel’s “final” boundaries, but are useful for observing urban growth and other topographical features.

Very fascinating read! I have seen similar articles and documentaries on the growth of other major metro areas (most notably Manhattan) over the years and the history of man’s battle against water.

It’s pretty amazing to think how practical concerns like transportation and access to water (for transportation, power, personal/industrial uses, and finally sewerage) determine where cities popped up geographically.